Fig. 6. Upon proteasome inhibition, hRUL138 steady-state levels in intact cells increase in a RING-dependent fashion. Transiently transfected Huh7 cells expressing GFP fusions of hRUL138 or the RING-deleted variant RUL1-1128 were treated for 6 hours with the proteasome inhibitor MG132, or DMSO alone, and equal aliquots from total cell lysates were analyzed by western blotting using a monoclonal anti-GFP antibody (left panel). The stabilizing effect of MG132 was also observed when the FLAG epitope instead of GFP was fused hRUL138; no signal at the corresponding position was detectable in nontransfected MG132-treated Huh7 cells (right panel).